Integrated, Chip-Scale RF Beamformer for an Optically-Fed Transmit Phased Array Antenna

This paper presents the design, layout, and characterization of a photonic integrated circuit (PIC) of an RF-beamformer for an optically-fed transmit phased array antenna. The PIC was made through the AIM Photonics Institute and has a response from 0–45 GHz. The design encompasses a coherent beamformer that utilizes a dual-path feed network to impose an analog phased difference between two correlated, but off-set optical beams. By imposing a relative phase delay between the two beams, a phase on the RF signal is realized upon down-conversion on a monolithically integrated Germanium photodetector. Subsequently, the photodetector outputs can be fed directly to the radiating elements of the phased array antenna. Demonstration of the beamforming network will be presented.